Actuators are used for a wide variety of purposes, for example for the actuation of valves or dampers in motor vehicles. The actuators may have an electric motor controlled, for example, by an electronic motor control unit (ECU). The electric motor can drive, for example, an actuating element, the positional variation of which, via a gear train, is detected by a position sensor. A supply voltage is required for the operation of such a position sensor.
In typical examples from the prior art, active position sensors for the positional detection or positional control of actuators are supplied with electrical energy (generally a voltage) by means of separate feeders. Accordingly, there are various output signals for the transmission of the actuator position. The known analog interface is ratiometric to the supply voltage. Consequently, the supply voltage, which is generated as a reference value in the control unit, must also be directly linked to the position sensor. A different situation applies in the case of supply voltage-independent (non-ratiometric) output signals from position sensors. In this case, the supply voltage does not necessarily need to be routed from the control unit, if the sensor can be supplied with energy by another means. However, a problem remains, in that a supply voltage which is separate from the motor, for example 5V, needs to be routed to the position sensors via separate feeders. The same applies to the recently introduced digital functions for the transmission of position signals in which, for example, a digital serial SENT protocol is used for a point-to-point connection (with no bus).
It will be understood that the provision of separate feeders of this type is a complex arrangement.
An actuator system is described in U.S. Pat. No. 5,389,864. In this system, the electrical energy for the operation of the position sensor is tapped from the control unit via the motor terminals of the motor control line.
A further actuator system with similar characteristics is known from U.S. Pat. No. 6,545,441 B1.
A connection circuit for a measuring device is described in DE 19947698 A1, in which the adjustment of a voltage supply by means of a power converter is described.